Joining together or holding of articles and/or materials has been common for at least thousands of years. Such joining has typically been achieved through use of adhesives of various types, e.g., exogenous substances applied between articles or materials to be joined which adhere to both of the articles or materials and, thus, join them. Today, modern adhesives are an integral part of life. Typical modern adhesives comprise what are known as contact adhesives. Such contact adhesives are usually based upon variations of soft sticky polymers of varying viscosity, which conform to surfaces and adhere through van der Waals forces, thereby joining surfaces/materials.
While such typical adhesives are quite useful, they do have a number of limitations. For example, the layer of adhesive necessary to join surfaces can be inconveniently thick (e.g., from hundreds of microns to millimeters, etc.). While that might be acceptable in some situations, it is quite inappropriate in others. Adhesives can also often leave messy residues. Additionally, adhesives can leak, spread or volatilize from their area of application into other nearby areas where they are not desired. Such spreading can result not only in unintended joining of materials, but can also result in chemical or physical contamination of such other areas.
Furthermore, while a wide range of adhesive compounds exists, the majority of them have a (sometimes limited) range of parameters necessary for their use. For example, some adhesives do not work above a certain ambient temperature (e.g., the polymers become too fluid and the adhesive either loses much of its adherent property or leaks away). Other adhesives do not work below a certain temperature (e.g., the adhesive becomes brittle and cracks). Additionally, many adhesives are toxic and/or cause irritation to body tissues which come into contact with them. Yet other adhesives do not adhere in the presence of water, organic solvents and/or vacuum, etc., while other adhesives require such conditions.
In addition to exogenous adhesive compounds, other adherents such as “hook and loop” or “touch fasteners'” e.g., Velcro®, have more recently been used to join materials together. However, such systems also are problematic in typically requiring two groups of specifically shaped fiber groups.
In the context of the above background, research on new adherents and methods of adhesion has been intrigued by examples of adhesion and adherent ability in the natural world. For example, the ability of geckos, spiders and flies to adhere to seemingly shear surfaces has long fascinated researchers. Geckos' ability to stick to surfaces without the use of an adhesive substance (such as a polymer, etc.) has been under intense scrutiny recently as a model for adhesion.
A welcome addition to the art would be an adherent material or surface or a method of adhesion which could be modified to fit different environmental conditions and parameters, which would not migrate to unwanted areas, which would not necessarily require two dedicated surfaces, and which would require no external application of resins, carriers, etc. The current invention provides these and other benefits which will be apparent upon examination of the following.